The long range objective of the proposed research is to understand the contribution of single cells in the visual system to the visual behavior of the animals and man. As a means of reaching this goal, electrophysiological data gathered from infra-human animals will be compared and correlated with human and animal psychophysical measures. Specifically, the proposed experiments are designed to link data obtained from single cells of cat visual cortex with psychophysical data from both humans and cats. The short range goals include: 1) behavioral measurement of the orientation sensitivity of the cat visual system, 2) electrophysiological studies of the orientation sensitivity of different classes of single cells in visual cortex of the cat and 3) orientation selectivity and preferences in the human visual system as a function of retinal position.